Ethylene can cause the premature death of plants or plant parts including, for example, flowers, leaves, fruits, and vegetables through binding with certain receptors in the plant. Ethylene also promotes leaf yellowing and stunted growth as well as premature fruit, flower, and leaf drop. Cyclopropenes (i.e., substituted and unsubstituted cyclopropene and its derivatives) are effective agents for blocking the effects of ethylene. Some useful methods of delivering cyclopropenes to plants or plant parts include forming a mixture that includes one or more cyclopropenes and water. However, in some of such mixtures, the activity of the cyclopropenes in the mixture is reduced. U.S. 2003/0224939 discloses the use of permeabilizing agents to improve the permeability of the cell walls of plants to certain specific plant growth regulators. It is desired to provide improved compositions that contain cyclopropenes and that improve the activity of cyclopropenes in mixtures that contain water and one or more such improved compositions; it is also desired to improve the effectiveness of blocking the effects of ethylene by cyclopropenes that are delivered to plants or plant parts by methods that use such compositions.